files                    External Collections of Data          Data Structure

    Pascal allows you to define files--that is, external collections of
    data. Three types of files are allowed: text files, data files, and
    untyped files.

    Text files are declared as follows:

         type
           <tname> = text;

         var
           <vname> : text;

    Text files are are accessed using Read, Readln, Write, and Writeln.
    All information in text files is stored as ASCII characters.
    Conversion to and from Integer and Real types is automatic.

    Text files consist of lines terminated by an end-of-line marker
    (CR/LF). Text files end with an end-of-file marker (^Z). They can
    only be processed sequentially, and simultaneous input and output is
    not allowed.

    Data files are declared as follows:

         type
           <tname>  = file of <basetype>;

         var
           <vname>  = file of <basetype>;

    where <basetype> is any data type or data structure except for a file
    type. Data files are accessed using Read and Write; data is kept in
    binary form at all times. Seek can also be used for random access of
    elements.

    Untyped files are allowed by Turbo Pascal and are declared as follows:

         type
           <tname>  = file;

         var
           <vname>  : file;

    Untyped files are accessed using BlockRead and BlockWrite, which allow
    transfers of large chunks in a single statement. Seek can also be used
    for random access of blocks.

  -------------------------------- Example ---------------------------------

           type
             MyRec = record;
               Cnt  : Integer;
               List : array[1..10] of Char;
               Flag : Boolean;
               Num  : Real
             end;

           var
             Iota : text;          { Iota is text file variable }
             Able : file of MyRec; { Able is data file variable }
             Fred : file;          { Fred is untyped file var }